Plans to widen a bridge over Broad Run are on schedule, but construction will depend on the presence of brook floaters, a species of freshwater mussels designated endangered in Virginia.
The Virginia Department of Transportation is scheduled to request bids this fall to replace and widen the Va. 28 bridge over Broad Run.
“The mussels have not affected the project’s schedule yet,” said Tom Fahrney, VDOT’s Prince William County liaison. “We’re still dealing with environmental agencies.”
Department of Game and Inland Fisheries officials said the stream should be surveyed to find out if the mussels could be relocated to protect them from being trampled during construction.
“In this case, we know there are mussels through the area, so that’s what we’re looking at,” said Ray Fernald, manager of non-game and environmental programs for the Department of Game and Inland Fisheries. “Relocation of mussels is general very successful.”
Va. 28 is one of the main roads that Prince William County and Fauquier County residents drive during morning and evening commutes.
The two-lane bridge is a bottleneck to traffic as more and more cars use Va. 28. Plans are in the works to widen other portions of Va. 28.
Fahrney said the widening project would add two lanes to the bridge and some extra space for an ultimate six-lane bridge.
In most cases, wildlife officials won’t recommend relocating an existing bridge to avoid an endangered species, said Fernald.
“In a major project normally you’re going to cause more impact by relocating a bridge than simply replacing it,” he said. “Generally, you’re better off utilizing the same corridor and minimizing the impact.”
The mussels have been documented in Broad Run as far back as 1991 and documentation from around the state indicates that Virginia has been a haven for freshwater mussels which filter water and whose shells provide habitats for other water creatures, said Brian Watson, a Game and Inland Fisheries biologist.
He said of the 1,000 species of freshwater mussels that exist, the U.S. provides habitats for 300, and 81 of those species can be found in Virginia.
Most are located in the southwestern portion of the state and the endangered brook floater, or alasmidonta varicosa, can be found in waters that lead to the Potomac, James and Shenandoah rivers, Watson said.
“It’s pretty rare in Virginia,” he said.
The brook floaters, who are filter feeders, actually live on the bottom of the stream and stabilize the stream bottom during floods and erosion activity, Watson said.
A Virginia Tech study in 1998 found brook floaters and four other species of mussels totaling over 2,500 within a 500-meter reach of the bridge, he said.
“Just based on the number of species in the area of Broad Run … that indicates to me the relative health of Broad Run seems to be good,” Watson said. “We treat that as a critical area as far as trying to protect wildlife.”
He said historical records indicated that Virginia’s stream bottoms were once covered in mussels, which can live up to 100 years.
But ultimately, the live mussels can’t just determine stream quality.
The creatures could just be old and no longer reproducing. That could be an indication that the species is dying out, said Watson.
Further surveys will determine the health of the mussels present, he said.
“Once you lose a species, they’re not going to come back to an area quickly,” he said.